Brake



April 1 1924. 1,488,714

c. SCHURMANN BRAKE Original Filed Dec. v. 1920 1:6 4.

INVENTOR.

A TTORNEY.

Patented Apr. 1 1924.

UNITED STATES 1,488,714 PATENT OFFICE.

CARL SCHU'RMLANN, OF D USSELD'ORF, GERMANY.

BRAKE.

Original application filed December '7, 1920, Serial No. 429,012. Divided and; this application filed February 3, 1923.

To all whom it may concern:

Be it known that I, CARL ScHI'iaMANN,

a citizen of German Republic, residing at Dusseldorf, Germany, have invented a new I and useful Brake, of which the following is a specification.

It is the object of my invention to provide a simple and effective bicycle brake, which acts efficiently and promptly and without lost motion to produce a braking action by back pedaling, while permitting forward pedaling without interference from the brake.

The present application is a division of my copending application Serial No. 429,012,

filed- December 7, 1920.

In attaining the aforesaid object in the embodiment of. my invention illustrated, I provide a rocking member which by its rocking in opposite'directions respectively sets and-releases the bicycle brake, as shown by being connected by a flexible member which includes a resilient member to a brake band which is wrapped around a brake drum on the rear wheel of the bicycle in the direction that thefriction produced upon the initial setting'of the brake tends to set the brake more tightly; and'this rocking member is co-axial with and abuts against a rotatable member which rotates with the pedal crankshaft, as by being carried by such crankshaft while saidrocking inember is carried by the frame concentric with the crankshaft; and between the rocking member and said rotatable member I provide a connection by a helical spring which has a driving connection with one of said members and fits in a recess in the other of said members to lock said two members together when they tend to rotate relatively in the direction to unwind the spring and to unlock them when they rotate relatively in the other direction; and in the preferred-form of my invention I provide such driving connection also by having the helical spring in a recess in the member with which said'helical spring has such driving connection, so that the helical spring fits into opposed recesses in the two members which it interconnects. The accompanyingdrawing illustrates my invention: Fig. 1 is a fragmental horizontal section, just. above the pedal crank-shaft, through the frame of a bicycle provided with my invention, the helical spring and associated parts being shown in peripheral Serial No. 616,735.

stantially on the line 33 of Fig. 1; Fig.

4. is a side elevation of the helical spring, in partial central longitudinal section; and Fig. 5 is an enlarged section somewhat similar to Fig. 1, showing one end of the helical spring bent to provide a positive anchorage.

The usual bicycle frame 10 has the usual wheels, of which only the rear wheel 11 is shown, and this rear' wheel is suitably driven, as by a chain 12 and suitable sprockets 13, from a pedal crank-shaft 14 suitably mounted in a crank-shaft bearing 15 provided in the usual manner in the lower part of the frame 10, the axle of the rearwheel 11 being provided with any known free-wheel device to permit the forward over-running of said rear wheel. The pedal crank-shaft 14 has the usual pedals 16 on the outer ends of the usual crank arms 17.

The axle of the rear wheel 11 is provided with a" brake drum 20 carrying a brake band 21, one end of which (the clockwise end as viewed from the left in Fig. 2) being fixed to a pin or bolt on the bicycle frame 10. The brake band 21 is laid around the drum 20 in the direction of turning, and is connected to a flexible member 24, such as a wire, which extends forward over a roller 25 mounted, on the lower part of the frame 10. Preferably the flexible member 24 includes a spring 23, shown as a tension spring. The forward end of the flexible member 24, after passing over the roller 25, passes downward and below and partially encircles a sleeve 26, which is provided with a suitable peripheral groove for receiving said flexible member, as is clear from Fig. 1. This sleeve 26 is a rocking member, rotatably mounted on the shouldered end 27 of the'hub or bearing 15 of the pedal crank-shaft 14, and may rock in the back-pedaling direction (or clockwise in Fig. 2) on said bearing 15 as far as permitted by the brake 21, while it is limited in its rocking movement in the other or forward pedaling direction counterclockwise in Fig. 2) by co-operatmg pins or studs 28 and 29 carried. by said sleeve 26 and bearing 15 respectively.

The crankarm' 17 adjacent to the sleeve 26 is provided with an enlarged hub- 31,

which thus rotates with the pedal crankshaftv 14. This hub 31 is shown as integral with the crankarm 17, but this is a mere incident as it need notbe made in that man- 5 ner. The hub 31 and sleeve 26 are close together, preferably overlapping each other,

and have cylindrical cavities opposed to or facing each other. A helical spring 32 fits into these cavities, so fitting them that it exerts only little outward pressure on the inner cylindrical faces of the cavities. Both ends of the helical spring 32 may be free to turn in the cavities in which they are respectively located, as in the constructions shown in Figs. 3 and 4; or, if desired, one end of the spring 32 may be permanently attached in its recess, as by an anchoring pin 33 such as shown in Fig. 1, or by the bent spring end 34 shown in Fi 5 and seated in a suitably located hole in the bot-. tom of said recess.

The helical spring 32 acts to permit relative movement between the sleeve 26 and hub 31 in one direction only, and to prevent such relative movement in the other direction. The direction in which such relative motion is'permitted is the forward-pedaling motion of the pedal crank-shaft 14, in which motion the friction of the walls of the spring-receiving recesses on the outer surface of the spring tends to wind up said spring, which tendency actually produces a suflicient winding up of the spring to release it from the Walls of the recesses, or.

from the wall of the recess ,in whichit is not permanently anchored if one end of the spring is anchored as shown in Figs. 1 and 5. The direction in which such relative motion is prevented is the back-pedaling motion of the pedal crank-shaft 14, in which motion the friction of the walls of the spring-receiving recesses on the outer surface of the spring tends to unwind said spring, which tendency actually produces .a sufficient unwinding of the spring to press such-spring with great firmness against the walls of such recesses, the firmness of which pressure increasesas the tendency to relative rotation in this direction is increased, so that the two members 15 and 31 are thus rigidly locked together upon any back-pedaling, and the pedal crank-shaft cannot turn in this back-pedaling direction without correspondingly turn-ing the sleeve 26. In consequence, the pedal crank-shaft 14 may be pedaled forward freely, as when so pedaled thedrag of the hub 31 tends to wind up the spring 32, and the sleeve 23 is moved in; the same direction only by the very slight fi frictional drag and by the action of the spring 23 ,and' the unwin ding of the brake band 21v until the pins 28 and 29 engage, at which time the brake. band 21 is released from the-drum 20. The-dragof the spring 32'on the hub'31'i practically negligible for forward pedaling, so that there may be free forward pedaling. However, as soon as back pedaling is started, the drag of the hub 31 on the spring 32 unwinds such springslightly,which locks the hub 31 and sleeve 15 together, so that such sleeve turns with said hub; and this turning of the sleeve 15 in the back-pedaling direction pulls forward the flexible member 24, which acts through the spring 23 to set the brake band21 on the brake drum 20. This brake setting is easily obtained, without great effort, because upon initial brake-setting thedrag of the drum 20 on the brake band 21 tends t assist. in the setting of the brake.

I claim as my invention:

1. A brake, comprising a rotary driven member, a otary driving membertherefor for driving the driven member forward, a brake for said driven member, a rocking member which by its rocking in opposite directions respectively sets and releasessaid brake, a rotatable member rotatable with said driving member, said rotatable member and said rocking member being co-axial and having axially abutting faces with alined circular recesses in them, a single helical spring fitting in said recesses to lock said co-axial members together when they tend to turn relatively in the direction to unwind said spring and to unlock them when they are turned relatively in the direction to wind said spring.

2. A brake, comprising a rotarydriven member, a rotary driving member therefor for driving the driven member forward, a

brake for said driven member, arocking member which by its rocking in opposite directions respectively sets and releases said brake, a rotatable member rotatable with for for driving the driven member forward,

said driven member having a brake drum, a brake band co-operating with said brake ,said driving member, said rotatable member and said rocking member being co-axlal and drum, a rockingmember co-axial with said driving member, a flexible member connecting said brake band to said rocking memher, said driving member including a memher which abuts axially against said rocking member, the axially abutting faces of said two abutting members having alined circular recesses in them; and a single helical-ispring fitting in said.- recesses to lock said co-axial members together when they tend to turn relatively in the direction to unwind said spring and to unlock them when they are turned relatively in the direction to wind said spring.

4. A brake, comprising a rotary driven member, a rotatable driving member therefor for driving said driven member forward, said driven member having a brake drum, a brake band co-operating with said brake drum, a rocking member co-axial wlth said driving member, a flexible member connecting said brake band to said rocking member, said driving member including a member in axial alinement with said rocking member, one of said axially alined members having a circular recess in its end face, and a single helical spring having a'driving connection with the other of said two co-axial members and fitting in said recess to lock said co-axial members together when they tend to turn relatively in the direction t6 unwind said spring and to unlock them when they are turned relatively in the'dir'ection to Wind said spring.

5. A brake, comprising a rotary driven member, a rotatable driving member therefor for driving the driven member forward, said driven member having a brake drum, a brake band co-operating with said brake drum, a rocking member coaxial with said drivin member, a flexible member connecting said brake band to said rocking member, the connection from said brake band to said rocking-member through said flexible member including a spring, said driving member including a member which abuts axially against said rocking member, the axially abutting faces of said two abutting members havingalined circular recesses in them, and a single helical spring fitting in said recesses to lock said co-axial members together when they tend to turn relatively in the direction to unwind said spring and to unlock them when they are turned relatively in the direction to windv said spring.

6. A brake, comprising a rotary driven member, a rotatable driving member there-' for for driving said driven member forward, said driven member having a brake drum, a brake band co-operating with said brake drum, a rocking member co-axial with said driving member, a flexible member connecting said brake band to said rocking member, the connection from said brake band to said rocking member through said flexible member including a sprin said drivmember including a mem er in axial ahnement with said rocking member, one of said axially alined members having a "for interconnecting sai for for driving the driven member forward,

said driven member having a brake drum, a brake band co-operating with said brake drum and wound around 1t in the direction age, a rocking member eo-axial with said driving member, a flexible member connecting-said brake band to said rocking member, and an over-runnin connecting device rocking member and said driving member when the driving member is moved backward and disconnecting them when the" driving member is moved forward. 7 f

8. A brake, comprising a rotary driven member, a rotatable driving member there for for driving the driven member forward, said driven member having a brake drum, a brake band co-operating with said brake drum, a rocking member co-axial with said driving member, a flexible member connecting said brake band to said rockin her, the cbnnection from said brake %and to said rocking member through said flexible of forward rotation from a fixed anchormemmember including a sprin and, an overrunning connecting device or interconnecting said rocking member and said driving member when the drivi member is moved backward and disconnecting them when the driving member is moved forward.

9. A brake, comprising a rotary driven member, a rotatable driving member therefor for driving the driven member forward,

said driven member having a brake drum,

over-running connecting device or interconnecting said rocking member and said driving member when the driving member is moved backward and disconnecting them when the driving member is moved forward.

CARL scHuRMAn 

